Scheffler, who can reclaim the world number one ranking with a win, started the day with a two shot advantage reached the turn at TPC Sawgrass at one-under thanks to a birdie at the ninth to stay top the leaderboard at 15-under ahead of Hatton who was in the club house with a seven-under 65.
Like Scheffler, Hatton could not get much going on his first nine reaching the turn at even par.
But the Englishman stepped on the gas after the turn, carding seven birdies, including five straight to close out his round.
Norway's Viktor Hovland (25), Australians Cam Davis (28) and Sung-Jae Im (24) sit five back of the leader with holes to play.
Lee started the day two back and immediately went to work rolling in a five-footer for birdie at the first to cut Scheffler's advantage to one.
Scheffler's first bogey of the day at the third would move Im into a share of the lead but the Australian's stay at the top would be brief. He crashed down the leaderboard after taking a triple bogey seven at the par four fourth.
Im's troubles began off the tee when he to punched out of the rough to set up what looked a routine third shot into the green.
But the ball would spin back into the water, leaving Lee to walk off with seven to hand Scheffler a three shot lead.
